Add a logic error that our tests miss

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Task

• Deliberately introduce a logic error into our code that our tests are unable to detect to further illustrate the limitations of our controller tests.

Steps

• Again, edit the app/controllers/limericks_controller.rb file, but this time to add a logic bug instead of a syntax error.
  • In the index method, replace the call to Limerick.all.reverse_order with a call to Limerick.take(2) (which returns a collection of Limerick objects containing only 2 limericks).

class LimericksController < ApplicationController

  before_action :authenticate_user!, except: [:index]
  before_action :require_permission, except: [:index, :new, :create]

  def index
    @limericks = Limerick.take(2)
    render :index
  end

  ...

• Note that this code now clearly contains a logic error—no matter how many limericks are in the database, the app will only ever display 2 of them; however, because we happen to have 2 Limerick test fixtures, the assertion assert_select 'div.card', limericks_size will not report a failure.

• Run all tests to check for errors.

rails test -v

• Inspect the output, which should look like this:

Running 1 tests in a single process (parallelization threshold is 50)
Run options: -v --seed 389

# Running:

LimericksControllerTest#test_should_get_index = 2.11 s = .

Finished in 2.112802s, 0.4733 runs/s, 0.9466 assertions/s.
1 runs, 2 assertions, 0 failures, 0 errors, 0 skips

• Note that the test indeed misses this logic bug.
  • The purpose of this example is to illustrate, yet again, the importance of writing tests that thoroughly test the code to minimize the number of bugs they might reasonably miss.
• Before moving on, correct the above bug.

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